Until 1610, the only known satellite was Earth's - the Moon. On that occasion, Galileo Galilei (1564-1642), with his telescope, discovered satellites orbiting the planet Jupiter. Today we know of dozens of satellites.
In astronomy, a natural satellite is a celestial body that moves around a planet thanks to gravitational force. For example, the gravitational force of the earth keeps the moon spinning around our planet.
Artificial satellites are objects built by humans (eg GPS satellites). The first artificial satellite was launched into space in 1957. There are currently several artificial satellites around the Earth.
The term "moon" can be used as a synonym for natural satellite of different planets.
A comet is the smaller body of the solar system, similar to an asteroid. It has a solid part, the core, composed of rocks, ice and dust and have varying dimensions (may be a few kilometers in diameter). They are usually far from the sun and in this case not visible.
They may become visible as they approach the Sun in their long course, sublimating the ice of the nucleus and releasing gas and dust to form the tail and "hair" around the nucleus. His best known is Halley, which regularly passes through our Solar System. Every 76 years, on average, it is visible from the earth. It passed through the Solar System region near our planet in 1986, which made it visible, so Halley should be back in 2062.